Method of detinning



c. F. CARRIER, 1R. METHOD OF DETINNING.

. APPLICATION FILED AUG.5', I911- RENEWED AUG. 7, 1920. 1,358,136.

Patented Nov. 9, 1920.

2 SHEETS-SHEET J.

R K R *1 T INVENTORi BY AHRRNEYS WITNESSES C. F. CARRIER, JR.

.rmnon or ninmmue. APPLICATION FILED AUG-5| 191l- RENEWED AUG; 7, I920.

2-SHEETS-SHEET 2.

vs INVENTOR ATTORNEYS UNITED STATES PATENT OFFICE.

COURTLAND F. cABnlER, JR, or onentnsrom wns'r vmenvm, ASSIGNOR TO THE VULCAN nn'rmnme' COMPANY, 01" SEWAREN, New JERSEY, A cQRPO AT' OF NEW JERSEY.

METHOD or DE'IINNING.

Specification of Letters Patent.

Application filed August 5, 1911, semi a... 642,470. Renewed August 7, 1920. Serial No. 402,030.

My invention relates to what is known as.

chlorin detinning an art which is founded upon the well known princi le that dry chlorin gas has a strong a nity for tin without affecting iron. Tin scrap when subjected to drychlorin may, by the proper application of this principle, have its tin surface converted into stannic chlorid, leav ing the iron substantially free from tin and unaffected by the chlorinor stann'ic chlorid. My invention has forits object to apply this well known principle on a commercial scale in such a manner as to obtain greatefiiciency of action and purity of product.

Heretofor e, in the carrying out of chlorin detinn ing on a commercial scale, many difliculties were encountered as the result of attempts to regulate the temperature in the apparatus in which the detinnj'ing operation is carried o n 'and also resulting from the pressures created in said apparatus. and from the manipulation of the materials. It is the object of the present invention to devise a process which dispenses entirely with those things heretofore recognized as creat-' ing defects, and. to devise a process Wl11Cl1 shall be continuous from start to finish, which shall operate practically automatically, and in which no regulation of temperature whatsoever is necessary and no pressures are created, and in which all of the elements of the process do their normal work without requirlng any positive manipulative control and without the creation of any unusual circumstances or conditions.

The apparatus in which my process may be advantageously carried out is illustrated in the drawings, in whicl1 Figure 1 illustrates in front elevation apparatus suitable for the practice of the invention;

Fig. 2 represents atop plan view thereof;

Fig. 5 represents a partial vertical sectainers therefor.

tion, on a somewhat larger scale, ofone of the op osite ends of adjacent c'yhnders bypipesand a closed series is formed by 01I11I1g the cylinder A with the cylinder A by the pipe E. The pipes D and E are.

provided, respectively, with hand-valves d and e The cylinders are also connected in parallel by means of the chlorin suppl pipe F; the air line G; the exhaust line PI; the by-pass line L; the double as line and the stannic chlorid line K. 11 of these lines are connected to each of the cylinders by means of branch pipes in which are 10- cated the hand-valves f, g, h, i, j, is, respectively. y

The gas line J has a connection to the top of each cylinder and at both ends of the cylinder, as shown, and a blower L is interposed in the line J at some convenient point between the two sets of connections; so that,

by. this arrangement, gas can be pumped from any one of the cylinders and blown into any other cylinder. at will. So also, the air may be supplied to any individual cylinder or cylinders by the air line Gr, connected with any suitable source of air supply. Furthermore, any of the cylinders may be suppliedwvith chlorin from the line F, and connections can be made from any of the cylinders with the lines H, I, and K, respectively, at will. As shown in the drawings, the chlorin line 1*, the by-pass line I, and the stannic chlorid line K are most conveniently connected to the bottom of each of the cvlinders at one end thereof, and the air line G and exhaust line H to the top of the cylinders at the other end.v

In the drawings, the cylinders are shown as in a horizontal position, which is preferable. especially. where they are of large size, for a number of reasons, particularly because when supported in the horizontal position, they can sustain to better advantage their own weight-and the weight of their contents of tin scrap and the con- It will. ofcourse, be understood that nevertheless, in many in- Patented None; 1920.

range the cylinders either at an incline or even in the vertical position, according to the requirements or convenience of local conditions. So also, the pipes D and E may either connect the tops of the cylinders, as shown, or they may connect the cylinders in any other suitable way, as, for instance, by joining the top of one cylinder with the bottom of the next in the series.

, The drawing illustrates a convenient number of cylinders but the number may'obvi ously be varied; for instance, a lesser number may be employed, although I do not recommend the employment of less than four. It is also to be understood that the cylinders'and various parts may of any convenient form and that they should be constructed of a material which will resist the action of the substances involved in the practice of the process.

The tin scrap to be treated is placed in suitable baskets or receptacles such as perforated iron, or screens. A sufficient number of these baskets is provided and they are of a size to fit the cylinders and to substantially fill the same. "Aaconxenient number.. 1s also kept in reserve at. all tunes. For

the purpose of illustration, I have shown in Fig. 5, one of the baskets partially filled. The scrap which fills these baskets is ordinarily cleaned by any conventional method and dried before it is placed in the cylinders and the baskets of dry scrap are placed in the cylinderswithout giving them an opportunity to condense moisture. from the air. The cylinders are closed when they are filled with this dry scrap and the lids 15 are fastened air tight. The valves in the pipe system are so arranged that a current of chlorin gas will be admitted to the cylinder A and such portions of this chlorin as are not'cousumed in the reaction in that cylinderwill pass on into the cylinder A and so on through the various cylinders. At the same time that the chlorin is admitted. the blower L is set in motion, thereby supplying the cylinder A with. a large volume of dry air which carries the chlorin through the cylinder A in a diluted condition. A large part of the diluted chlorin will react with the tin on the scrap and form stannic chlorid which being liquid, trickles to the bottom of the cylinder and is withdrawn through the line H. The valve 9' on cylinder A 5 being open, the air that may be contained in the cylinders originally will be forced through the line J into the cylinder A The cylinder A", in addition to having this connection to the line J. also connects with the cylinder A, and

the cylinder A is open only to the exhaust line H. The connection through E between cylinders A and A is closed and the gases whlch escape from A pass out of the sys tem where they may be subjected to further treatment for the recovery of any valuable constituents. The volume of air supplied through line J is exceedingly large compared with the volume of chlorin so that the chlorin in the system at that period of the operation'is throughout in a state of great dilution. y v I When the detin'ning operation is started originally, it will be noted that the scrap has its full coating of tin in each of the cylinders. The chlorin. being very dilute attacks this coating of tin and converts it into stannic chlorid (SnCh). As the reaction proceeds, a point will finally bereached where the dilute chlorin which has hasnbeenadmitted in the cylinder A will no longer react with any of the tin contents of the.

scrap and when that point has been reached,

inder 1 is closed, and the connection between J and the cylinder A is opened. The supply of strong chlorin to Af i cone tinned. The effect of this is that the cylinder A will be filled with chlorin of maxi? mum strength which, following immediately upon a condition of great dilution of chlorin removes'fi'om the'scrap in the cylinder A the remaining portions of tin. The surplus of concentrated chlorin passes through the line D into the cylinder A where it is again diluted as it had been in the cylinder A by a large volume of air from the pipe J.

Xext. the valve (1 in the pipe D which connects cylinders A and A flis closed. The chlorin is shut 01f from cylinder A and admitted into cylinder A In order to clear cylinder A of chlorin, the bypass connections are made between cylinders A and A and air is admitted through the air line (i of the line J is closed. In this way, cylinder A has become the first of the series and cylinder A the last of the series. By the time these connections have all been made, the diluted chlorin in cylinder A has-finished itswork and that cylinder is ready for the strong chlorin treatment which proceeds as before described in connection with cylinder A and so on throughout the system.

The chlorin which is employed in this process should be dry when used. It may pass out of thesystem without entering into.

be derived from any convenient source. If produced from a commercialchlorin generating battery system the chlorin will coritain a fairly large amount ofair, the other hand, 'practically pure chlorin may be supplied from liquid chlorin containers or any other source. The air that is used shouldalso bethoroughly dry. The air that is used for clearing the cylinders of their remaining contents of chlorin gas is preferably dry, dehydrated, warm air. Such chlorin as escapes from cylinder A? into cylinder A is in a dilute condition even after all reaction in' the cylinder A has ceased and as this diluted, chlorin passes through theses ries, itdisplacesjany, aii orgas thatmay contained in. all of theother cylinders and pushes it forward. There i sfan increasing quantity of tin on the scrap gather the cylinders in the series, the last cylinder being obvionsly to a', dilute chlorin treatment in presence of an encess of tin that practically none of the chloriii can the reaction with-,tl etin. p

It will rey dily; seen that, the process described, the detinning operation is con:- ducted unifol' inly and continuously, such conditions being favorable to uniformity bf result, The main oderative advantage of the process is to be oli id hoivever, the separation of the operations into separate successive stages each of ivhichis peculiarly adapted to .the work ;it is to accomplish. Thus it win ng een that one eylinder, \vill be in the absorption stage, three win the detinning stage, and onein vthe finishihg' stage, and. the sixth cut out for fume remoral and refilling. It \villalso be seen that the operation is so conducted that the fresh scrap is first treatedvwith extremely diluted chlorin produced as residual ,gas from theearlier stages of thepro'cess. This starts the detinning and there is a large excess of tin present only va m nimum j amount of chlorm if any,' c anj' escape.v In

the next stage, a dilute. .chlorin formed by the impoverishment of the gaseous mixture before reaching that, stage will have a slightly stronger efiect ;.but.still within the limits of very dilute chlorin. In the next stage, detinning is completedso far as dilute .chlorin can accomplish it and in the final stage by a sudden injection of concentrated chlorin following the dilute chlorin treatment the remaining-portions of the tin are removed. e

The efliciency of such a process isgreatly influenced by the state of rest or the state of motion' of the gases during the several stages of the operation. The absorption stage ismore complete and eflicient if the dilute chlorin is in a state of comparative rest or quiet. Under such conditions owing to'the greater density of the 'chlorin' the gas will become less dense than before and there ivillbe constant tendency to stratification in; the vessel, the less dense portions of the gaseous mixtures rising progressivelyabove those portions which; contain larger per-- centages of chlorin. I If, therefore, the gases the absorption stage be kept as quiescent aspossible the gases escaping from the vess el will contain minimum percentages of ehlorin. F or this reason it is preferred to keep the gases in as quiescent a state as posduringthe ahshrption. The ,detinning stage has 'considerably different requirements. The reaction between chlorin and. tin generates heat and ifth' is is lo alizeanm iron as weuasaeaa be res me T 16- cahzati on of hea is; p ssib e when the gases are a quiescent state, but if the gases ed ma s heaais difiused no such is e f t nj r lame p e 'y. the; es i noents a a: sea an e f nsthwle hni a S he b i fiii of the chlorin in, the gas is substantially the sam par l amass. b a, t e. re s n are t e a, n. pa s. s ueaesasiysa a the seat-as uniform airbags.

out the apparatus,

n quahityp mpe i i e betwe n mowin 1n thesystem would be qlllck lyi balanced by the circulat ng gases, any serious inequality of tempera ur cannot, arise, .velt tempo- 'alloy is not attacked by dilute chlorin but is attacked] by strong v ch'loi-iii. 'lhe finishing stage of, the operat on.involving the eni- 'lbymeat of concentrated chlorin is. {lief-eore, necessary inprder to obtain the my, mum detinning effect; ainhiniasnnich as full penetrationpf thc lmass of the tin scrap not so, readily attained during the circulating stage tvhereindilnte chlorin employed. the quiescent stage made available fm; a complete penetration of the mass by displacement n'ith' theeqncen tratcd rhlorin.

Theexi'gencies of the finishing stage are somewhat analogous to those of the abs-e11)- tion'stage. The stratification principle is therefore, mad euse of in this tso, The difference in density between aii and dilute chlorin is not sufficient to disphlee the air from the interstices of the scrap while the gases are in motion. By maintaining'the gases through the finishing stagein a. substantially quiescent state, however. the less It isjl so ta be noted v dense gases are displaced and the heavy, concentrated chlorin readily penetrates the scrap. In' thismanner, the gases and the strong chlorin are brought into contact with all portions of the tin. It is also much easier to increase the concentration of the chlorin to full strength by displacing in a the tin being removed by dilute chlorin, is

readily removed at temperatures far below those at which chlorin and iron unite, so

' that by the time the concentrated chlorin treatment is reached, there is not sufficient tin on the scrap to produce abnormally hlgh temperatures. This is the result of treating the fresh scrap first with the residual gases from the other parts of the process, then with diluted chlorin of slightly increasing concentration until nearly all of the .tin is removed, and finally, removing the maximum' amount of the remaining tin in a finishing stage by means of very concentrated chlorin. The proportion of neutral gases in the dilute chlorin is so great that the heat of the reaction is carried away by the depleted gases which are displaced by the fresh supply of highly diluted chlorin, for which reason it is impossible to overheat the scrap, and consequently no temperature control'whatever is needed.

The essence of this invention, therefore, consists in a detinning' process in which, once in working order, the fresh scrap .1S treated under conditions of chlorin dilution, the last period of which is a chlorin in a high state of dilution; second, in following this dilute chlorin treatment, immediately with a concentrated chlorin treatment; and

third, in creating in the process the appropriate conditions of rest and motion for the periods of absorption, detinning and finishing. These three "features which are simultaneously present in the process as above described, result in a chlorin detinning process which, as described, is practically continuous and free from all complications such as temperature regulation or graduations of pressure .or any special treatments. The entire process proceeds normally and withoutv the creation of any unusual conditions.

Having thus described my invention, what I claim is: r 1. The method of detinning tin-scrap, whichconsists in treating the scrap in separate portions, in separate, successive stages,

first with dilute anhydrous chlorin, until the major portion of the tin is removed, the dilution of'the chlorin thus employed being so extreme that reaction with the iron of the scrap under the conditions prevailing is impossible, and finishing the detinning with concentrated chlorin; substantially as described. Y a

2. The method of detinning tin-scrap, which consists in treating the scrap in separate portions, in separate, successive stages,

first with dilute chlorin, until nearly all of the free tin is removed, the degree of dilution of the chlorin thus employed being such that under the prevailing conditions reaction between the iron and the scrap is impossible, maintaining said degree of dilution practically uniform, and finishing the detinning with concentrated chlorin.

3. The method of detinning tin-scrap, which consists in simultaneously treating separate portions of the scrap with dry.

chlorin of widely diflerent degrees of concentration (i. e., highly dilute and highly concentrated chlorin), in separate successive stages; substantially as described.

4. The method of detinning tin-scrap by means of chlorin which consists in treating 6. The method of detinning tin-scrap by.

means of dry chlorin gas which consists in first utilizing the scrap to absorb residual chlorin, continuing the detinning with dilute chlorin until the major portion ofthe tin is removed, and completing the det-inning by the abrupt admission of an excess of concentrated chlorin; substantially as described.

7. The method of detinning tin scrap, which consists in carrying on the detinning operation by operating upon separate ortions of the scrap in successive preliminary' stages in the presence of dilute chlorin of gradually increasing concentration, and abruptly finishing the detinning in the presence of chlorin of a still higher degree of concentration; substantially as described.

8. The method of detinning tin-scrap'bymeans of gaseous mixtures, which consists in treating the scrap with a moving body of gas, and then with a quiescent body thereof; substantially as described.

9. The method of detinning tin-scrap by means of gaseous mixtures, which consists .gaseous mixtures containing described.

I 11. The method of detinning tin-scrap by means of gaseous .mimures, which consists in treating successive, separate portions of the scrap withthe" gas in varying states of rest and motion; substantially as described. 12. The method of detinning tin-scrap by means of gaseous mixtures, which consists in treating successive, separate portions of the scrap with the gas invarying states of rest and motion, the gas in the state of motion being diluted with gases previously used in the operation; substantially as described.

13. The method of detinning tin-scrap, which consists in treating the scrap with a circulating body of dilute chlorin, and finishing the detinning by treating the scrap with an excess of strong chlerin in a relatively quiescent state; substantially as described.

14. The method of detinning tin-scrap, which consists in treating the scrap with a circulatin body of chlorin which has been diluted with the residue of gases previously used in the operation and then finishing the detinning with strong chlorin in a relatively quiescent state; substantially as described. 15. The method of detinning tin-scrap, which censists in treating the scrap with;a body of rapidly circulating dilute chlor n to remove the bulk of the tin, removing the maximum amount of the remainingtin by treatingthe scrap with a large excess of strong chlorin in a relatively quiescent state,

and recovering the maximum amountof the residual chlorin by treating the same with an excess of tin, while in a relatively quiescent state; substantially as described.

16.The method of detinning tin-scrap, which consists in treating the scrap with hlor n the gases being in a comparatively quiescent state when either the amount of free tin or chlorin approaches a minimum, and in such rapid state of circulation when considerable quantitis of both tin and ehlorin are present that the circulating chlorin gas mixture will be substantially uniferin through-' out; substantially as described.

Th th d of hhnin inap, which consists in removing the greater portion of the tin with dry chlorinof such extrfme di utio hat .unde th Pr a i g conditions reaction with the iron of the scrap is impossible, and removing the maximum amount ofthe remaining tm with concentrated chlorin substantially as described.

1 8. The method of detinning tin-scrap, Wh1ch consists in first partially detinning a mass of scrap with chlorin in a stateof di lution closely approaching an inert condition, and subsequently detinning such partially detinned mass to an extent sufficient to Practically remove itsrmaining free tin contents by chlorin of such extreme dilution a nd th Pr il n cond ns action with the iron of the scrap is impqssible; substantially as described.

19. The method of detinning tin-scrap, which consists in first partially detinning a mass of scrap withchlbrin in a state of dilution closely approaching an inactive con dition, and subsequently .detinning such Partia ly d' t ned me fi s w h i u hlo'rin of a Str n th e th n that ficient practically remove its remaining free t n cont nt and h Comp et the remoyal of saidfree tin, by means of chlorin O ll hexh m diluti t at nd r h p er vailing conditions reaction with the iron of the scrap is'impossjible; substantially as described.

20. The method of detinning tin-scrap, which consists in detinning a mass of scrap ith flute hlo in d i ngth par y S n as s of a fur h p an f h chlorinpcontents, then treating a mass of fresh-scrap with said gases. thus depleted, andthen detinning said partially detinned fresh scrap with dilute chlorin of greater. strength; 'substantially as described.

21! T t imprqvlembnt in he method o e nn l tin-sk mp b di u hlo which consistsin giving the fresh scrap a prelimihary reatm t wi h l l i di t d a state clpsely approximating an inert condio emplo n a po f h resul a gases asa diluent for chlorin andemploying thechlerin thus dil ted to remove furr portions of tin f qm a d p rt a lyd tinned fresh scrap; substantially as described.

- 22. That improvement in the method of d nn ng tin-s rap w h dilute n, which s pnsi ts l edu ng ilnte chlorin mp y d as t e a ti d in age t to a tate of extreme lut on, a ng m -h 1'15 eration inthe first charge by the admission of chlorin gas diluted with air; decreaslng the air dilution of th gas thus admitted as the detinning in saidcharge progresses; passing the gases from the first ehargesuccessively through the other charges of the series as the after the completion of the detinning operation in the first charge into one of the charges utilizing dilutechlorin; substantially as described. i v

v 24. The method of 'detinning tin-scrap, which consists in establishing a series of separate charges to be treated; starting the operation in the first charge by'the admission of chlorin gas'diluted with air; decreasing the air dilution of the gas thus admitted as the detinning in said charge progresses; pass- I ing chlor1n gas through, a succession of tanks ing the gases from the first charge successively through the other charges of the series as the detinning in the first charge proc'eeds;.

finishing the detinning of the first charge by concentrated'chlorin; and finally by-passing the residual gases left after the completion of the detinning operation in the first charge into one of the charges utilizing dilute chlorin; substantially as described.

25. The method of detinning tin scrap, which consists in establishing a series ofseparate charges to be treated; startingthe operation in the first charge by the admission of chlorin gas diluted with air; decreasing the air dilution of the gas thus admitted as the detinning in said charge progresses ;passing the gases from the first. charge successively through the other charges of the series as the detinning in the first charge proceeds; and finally by-passing, by means of a diluting current of Warm, dry air, the residual stages of detinning,by introducing such inert gas to the tank containing the detinned scrap,

and admitting fresh chlorin to a subsequent tank, the inert gas admixing therewith and being circulated serially through the successive tanks.

the chlorin to a subsequent tank'in the series,

whereby it forms'a mixture with the inert gas, and circulates therewith until the chlorin is removed therefrom by combining with the tin. I

28. The process of detinning by circulatuntil the chlorin is removed by combining with the tin.

- 29. The process of detinning by circulating chlorin gas through a succession of tanks containing tin scrap in varying stages of detinning, which consists in coupling said tanks in series except for one tank which is isolated from such series, opening said tank, removing the detinned scrap, recharging with fresh scrap and again closing it while the detinning operation is proceeding in the remaining. tanks, then coupling the newly charged tank into'the. series and isolating therefrom the next succeeding tank for recharging, applying a suction each time at the outlet of the newly charged tank, admitting air to the tank longest charged with scrap. and admitting chlorin to a subsequent tank so that the chlorin and air may mix and be drawn together through the series of tanks.

In testimony whereof I afiix my signature in presence of two Witnesses.

GOURTLAND F. CARRIER, Jn.

.Witnesses: a

MINERVA LOBEL, M. AcNUs BILL. 

